內輻射帶質子通量與太陽黑子數及宇宙射線關係分析

Analysis on relations of energetic proton fluxes in the inner radiation belt, sunspot numbers, and cosmic ray intensities

陳彥翔(Yan-Xiang Chen)

指導教授 ： 汪愷悌

淡江大學/工學院/航空太空工程學系碩士班/碩士(2022年)

https://doi.org/10.6846/TKU.2022.00393

摘要

本研究透過范艾倫探測器衛星任務酬載之相對質子光譜儀於內輻射帶觀測之能量高於400百萬電子伏特之質子微分通量資料，分析其與太陽黑子數及宇宙射線之間的相關性，以推測觀測之質子來源。過去很少有衛星任務長時間觀測內輻射帶區域並量測幾百萬電子伏特以上能量的質子，因而運用以上酬載之觀測資料來研究對了解此區域高能質子形成的輻射環境會很有幫助。本研究中分析的資料時間範圍為2012年10月至2019年6月，以月平均值求其交叉相關係數。研究結果顯示，1325百萬電子伏特之能量頻道觀測之質子微分通量與宇宙射線則有超過95%信賴區間的正相關性，所以此能量頻道量測之質子來源應為宇宙射線。另外，529、600、683百萬電子伏特這三個能量頻道的質子微分通量對太陽黑子數有呈現出超過95%信賴區間的正相關性，而783、907百萬電子伏特這兩個能量頻道的相關性並不明顯，因此，推測前三個能量頻道的質子可能來自太陽活動所噴發而來的，而後兩個能量頻道的質子來源可能是太陽活動和宇宙射線混合的。至於在交叉相關係數的研究結果中，雖然有顯示內輻射帶觀測質子通量可與前數月的太陽黑子數呈現最大的相關性，但數值差距與以當月太陽黑子數為基準所得結果差距相當小，因此不能斷言其絕對性，這個部分的觀察可能需要更長時間的觀測資料才能有更準確的結論。本研究結果可以做為內輻射帶高能質子來源的參考。

關鍵字

內輻射帶 ； 質子微分通量 ； 太陽黑子 ； 宇宙射線 ； 交叉相關係數

並列摘要

In this study, the observational data of differential fluxes of protons with energies higher than 400 megaelectron-volts in the inner radiation belt measured from the Relativistic Proton Spectrometer on the Van Allen Probe satellite mission are adopted to analyze their correlations with sunspot numbers and cosmic rays. This allows to infer the sources of the observed protons. Indeed, very few satellite missions had performed long-time observations on protons with energies above several million electron volts in the inner radiation belt region for a long time. Hence, it is very helpful to analyze the aforementioned observations to understand the radiation environment from these energetic protons. The data observed from the year of 2012 to 2019 are analyzed and the cross-correlations are acquired from the monthly mean values. The results show that observed differential fluxes of protons with 1,325 megaelectron-volts have a positive cross-correlation with cosmic rays at a confidence interval more than 95%. Therefore, protons at this energy level can be from cosmic rays. On the other hand, the differential fluxes of protons at 529, 600, and 683 megaelectron-volts have positive correlations with sunspot numbers at a confidence interval more than 95% while the differential fluxes of protons at 783 and 907 megaelectron-volts have little correlations. Therefore, the source of protons of the above former three energy levels can be inferred as from solar particles but protons of the latter two energy levels can be inferred as from a mixture of solar particles and cosmic rays. As for the results of cross-correlations, the largest correlation occurs when the observed proton fluxes are related to the sunspot numbers of a few months earlier, but the numerical gap is so small that no solid conclusion can be addressed. This issue requires further analysis based on longer-time observational data. The results of this study can be referred for the sources of energetic protons in the inner radiation belt.

並列關鍵字

inner radiation belt ； differential flux of protons ； sunspot numbers ； cosmic ray ； cross correlation

參考文獻

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